Upon starting my paper tuning I built a similar rig but then started using a discarded real estate sign placard holder. I use the black office clips to hold newspaper to the frame. Its good for staking in the ground outside. I shoot mainly at night in the garage (after kids go to bed) so I filled two 5gal buckets with sand and they hold as an excellent reinsertable bases.

Id like to rig up something with a paper scroll so I can scroll new paper versus clipping newspaper sheets. I can get about 10 shots before it gets too crowded for good tears.